Conventional intravenous catheter apparatus includes a hollow syringe needle and a close-fitting surrounding sheath from which a point of the needle initially projects. The needle point and sheath are inserted into a vein so that blood back-flows through the needle into a transparent hollow push-pull element, usually cylindrical and somewhat elongated, fixed on the needle remote from its point. The appearance of blood within that transparent element indicates that the needle and sheath have been properly inserted in the vein. Typically there is a cylindrical elongated vial coaxially located on the end of the sheath and the needle initially extends coaxially through a circular end opening in the vial and through the sheath. After proper insertion in the vein the needle is then withdrawn from the sheath and from the vial through the opening in the vial and is discarded. The end of a flexible tube is then fitted into the vial opening to communicate with a source of intravenous fluid.
This conventional intravenous catheter design has been improved as described in my co-pending parent application by providing a diaphragm over the end of the vial through which the needle is initially inserted. Blood which back-flows into the vial after the needle is removed cannot advance farther beyond the diaphragm and leakage of blood from the vial prior to introduction of the intravenous fluid is thereby prevented.
However, a wholly separate problem remains. that is that the unprotected point of the removed needle withdrawn from the sheath and contaminated with blood can be a source of If accidental injury. The principal purpose of the present invention is to provide a protective enclosure for the needle to prevent accidental injury of that kind.